This invention relates in general to solar heating and more particularly to a solar heating system for buildings, to the combination of a solar collector and manifold, to a collector panel itself, and to a method and apparatus for installing the collector in a position suitable for absorbing energy from the sun's rays.
With the dramatic increase in the cost of fossil fuels, particularly heating oil and natural gas, the heating industry has turned to solar energy as a less expensive means for satisfying the heating requirements of buildings. A wide variety of solar heating systems, and particularly collectors for such systems, have been developed in recent years. Most are quite expensive, difficult to install, and once in use create a multitude of maintenance problems.
The typical solar heating system includes several collectors that are positioned such that the sun's rays impinge upon them. These collectors contain fluid passages that terminate at suitable fittings. The collectors are normally manufactured at a central facility and then shipped to the construction site where they are connected together with pipe much in the same manner that a plumber connects conventional plumbing fixtures into a household plumbing system. This field installation is expensive. Moreover, the heat transfer fluid which flows through collectors and the associated piping is usually exposed to only a relatively small heated area, for the passageways to which it is confined are usually behind only a small proportion of the actual area that is heated. Also the heat transfer fluid is usually water or an antifreeze. Water will freeze and destroy the collectors and piping system unless provisions are made to completely drain the collectors and associated piping when the collectors are not collecting heat. Antifreeze is somewhat expensive in its own right, and tends to undergo chemical change at the elevated temperatures which are often encountered during summer months. In addition, special precautions must be taken to insure that the heat transfer fluid containing the antifreeze does not escape into the water and forced air systems of the building, for many antifreezes are toxic. This precludes the use of single wall heat exchangers.
Aside from the foregoing, most solar energy systems of present development utilize specially constructed heat reservoirs which are to a large measure permanent built-in installations. For example, some take the form of rock beds to which the heat from the heat transfer fluid is dissipated. Usually air from the forced air heating system for the building is directed through the rock beds to extract the heat from the rocks and thereby elevate the temperature of the air. Rock beds require special pits that must be dug either adjacent to the building that is to be heated or within its basement, the latter being normally practical for only new construction. This is an expensive procedure. Furthermore, the bed being within the ground, absorbs ground moisture and becomes moldy, and this imparts a musty odor to the air that is forced through the bed. Also the beds attract insects and other creatures, such as snakes, all of which have no place in a good ventilating system. Other reservoirs take the form of large water tanks which are normally installed during the construction of the building. These tanks are expensive and difficult to service. Moreover, they will in time deteriorate to the extent that they are no longer operable, yet because of their size they cannot be removed from the building without being cut apart. In most instances the water tanks are cylindrical. When outdoors they appear unsightly and are difficult to insulate. When indoors they do not utilize the available space efficiently.
Furthermore, it is not uncommon to find a large number of pumps and flow control valves in solar heating systems of present manufacture. These pumps add significantly to the initial cost of these systems, not to speak of the maintenance problems that they subsequently create. The valves, which are supposed to distribute the heat transfer fluid evenly to all collectors, are difficult to adjust and often do not adequately serve the purpose for which they are installed.